Distances shorter than 1 pm

This page lists lengths shorter than 1 picometre (10⁻¹² m).

Femtometre scale

• 1 × 10⁻¹³ metres = 100 fm = 0.1 pm.
• ≈ 1 × 10⁻¹³ metres = 1 x unit
• 1 × 10⁻¹⁴ metres = 10 fm
• 7 fm - the radius of the effective scattering cross section for a gold nucleus scattering a 6 MeV alpha particle over 140 degrees^[1]
• 2.81794 fm — classical electron radius^[2]
• 1.5 fm — diameter of the Scattering Cross Section of an 11 MeV proton with a target proton^[1]
• 1 × 10⁻¹⁵ metres = 1 fm = 1 femtometre = 1,000 attometres

Attometre scale

• 850 am = 0.85 fm — approximate proton radius^[3]
• 1 × 10⁻¹⁶ metres = 100 am
• 1 × 10⁻¹⁷ metres = 10 am
• 1 × 10⁻¹⁸ metres = 1 am = 1 attometre = 1,000 zeptometres
• 1.0 am — sensitivity of the LIGO detector for gravitational waves.^[4]

Zeptometre scale

• 310 zm — de Broglie wavelength of protons at the Large Hadron Collider (4 TeV as of 2012)
• 1 × 10⁻¹⁹ metres = 100 zm
• 1 × 10⁻²⁰ metres = 10 zm
• 7 × 10⁻²¹ metres = radius of effective cross section for a 250 GeV neutrino scattering off a nucleon^[5]
• 2 × 10⁻²¹ metres = radius of effective cross section for a 20 GeV neutrino scattering off a nucleon^[5]
• 1 × 10⁻²¹ metres = 1 zm = 1 zeptometre = 1,000 yoctometres

Shorter than 1 zm (10⁻²¹ m)

• 1 × 10⁻²² metres = 100 ym
• 2 × 10⁻²³ metres = 20 ym, the effective cross-section radius of 1 MeV neutrinos as measured by Clyde Cowan and Frederick Reines^[6]
• 1 × 10⁻²³ metres = 10 ym
• 1 × 10⁻²⁴ metres = 1 ym = 1 yoctometre, the smallest named subdivision of the metre in the SI base unit of length.
• 1.62 × 10⁻³⁵ metres = the Planck length (lengths smaller than this do not make any physical sense, pending a working understanding of quantum gravity)

See also

• SI prefixed forms of metre (yoctometre, zeptometre, attometre, femtometre, picometre)
• Orders of magnitude (length)

References

1. Carl R. Nave. "Scattering Cross Section". Retrieved 2009-02-10.
2. NIST. CODATA Value: classical electron radius. Retrieved 2009-02-10
3. Randolf Pohl, Aldo Antognini, François Nez, Fernando D. Amaro, François Biraben, João M. R. Cardoso, Daniel S. Covita, Andreas Dax, Satish Dhawan, Luis M. P. Fernandes, Adolf Giesen, Thomas Graf, Theodor W. Hänsch, Paul Indelicato, Lucile Julien, Cheng-Yang Kao, Paul Knowles, Eric-Olivier Le Bigot, Yi-Wei Liu, José A. M. Lopes, Livia Ludhova, Cristina M. B. Monteiro, Françoise Mulhauser, Tobias Nebel, Paul Rabinowitz; et al. (8 July 2010). "The size of the proton". Nature 466 (7303): 213–216. Bibcode:2010Natur.466..213P. doi:10.1038/nature09250. PMID 20613837. Retrieved 2010-07-09.
4. gravitational waves that originate tens of millions of light years from Earth are expected to distort the 4 kilometer mirror spacing by about 10⁻¹⁸ m, less than one-thousandth the charge diameter of a proton. Equivalently, this is a relative change in distance of approximately one part in 10²¹. "On September 14, 2015 at 09:50:45 UTC the two detectors of the Laser Interferometer Gravitational-Wave Observatory simultaneously observed a transient gravitational-wave signal. The signal sweeps upwards in frequency from 35 to 250 Hz with a peak gravitational-wave strain of 1.0×10⁻²¹." B. P. Abbott et al. (LIGO Scientific Collaboration and Virgo Collaboration), "Observation of Gravitational Waves from a Binary Black Hole Merger", Phys. Rev. Lett. 116, 061102, published 11 February 2016.
5. Carl R. Nave. "Neutron Absorption Cross-sections". Retrieved 2008-12-04. (area for 20 GeV about 10 x 10⁻⁴² m² gives effective radius of about 2 x 10⁻²¹ m; for 250 GeV about 150 x 10⁻⁴² m² gives effective radius of about 7 x 10⁻²¹ m)
6. Carl R. Nave. "Cowan and Reines Neutrino Experiment". Retrieved 2008-12-04. (6.3 x 10⁻⁴⁴ cm², which gives an effective radius of about 2 x 10⁻²³ m)